Fix nil ptr bug

pkg/loader/fileloader.go

@@ -267,7 +267,8 @@ func (l *fileLoader) errIfArgEqualOrHigher(
 // path but a different tag?
 func (l *fileLoader) errIfRepoCycle(newRepoSpec *git.RepoSpec) error {
 	// TODO(monopole): Use parsed data instead of Raw().
-	if strings.HasPrefix(l.repoSpec.Raw(), newRepoSpec.Raw()) {
+	if l.repoSpec != nil &&
+		strings.HasPrefix(l.repoSpec.Raw(), newRepoSpec.Raw()) {
 		return fmt.Errorf(
 			"cycle detected: URI '%s' referenced by previous URI '%s'",
 			newRepoSpec.Raw(), l.repoSpec.Raw())

pkg/loader/fileloader_test.go

@@ -455,3 +455,29 @@ func TestLoaderDisallowsLocalBaseFromRemoteOverlay(t *testing.T) {
 		t.Fatalf("unexpected err: %v", err)
 	}
 }
+
+func TestLocalLoaderReferencingGitBase(t *testing.T) {
+	topDir := "/whatever"
+	cloneRoot := topDir + "/someClone"
+	fSys := fs.MakeFakeFS()
+	fSys.MkdirAll(topDir)
+	fSys.MkdirAll(cloneRoot + "/foo/base")
+
+	root, err := demandDirectoryRoot(fSys, topDir)
+	if err != nil {
+		t.Fatalf("unexpected err:  %v\n", err)
+	}
+	l1 := newLoaderAtConfirmedDir(
+		root, fSys, nil,
+		git.DoNothingCloner(fs.ConfirmedDir(cloneRoot)))
+	if l1.Root() != topDir {
+		t.Fatalf("unexpected root %s", l1.Root())
+	}
+	l2, err := l1.New("github.com/someOrg/someRepo/foo/base")
+	if err != nil {
+		t.Fatalf("unexpected err:  %v\n", err)
+	}
+	if l2.Root() != cloneRoot+"/foo/base" {
+		t.Fatalf("unexpected root %s", l2.Root())
+	}
+}